Recently, Fishman and his colleagues have found a low frequency feature in the admittance (or impedance) of squid axon membranes which cannot be accounted for by the usual Hodgkin-Huxley formalism. Two physical processes which slightly modify the usual HH formalism have been proposed to explain this low frequency feature by Fishman and his colleagues. One process involves the addition of an inactivation to the HH K ion kinetics. The other involves the K ion accumulation outside the axon membrane. In our work, we have shown that the experimental low-frequency feature can be simulated easily with a "nonequilibrium" channel model. This model differs from the original Hodgkin-Huxley formalism and the modified models mentioned above in that this model requires an energy source to maintain a nonequilibrium steady-state. In squid axons, the electrochemical gradients of K ion and Na ion may serve as energy sources.